def demo(obj):
    print("形参值:",obj)
    obj += obj
    print("形参值:",obj)
    #调用函数
    print ("=======值传递=======")
    string = "这是第一个测试"
    print("调用函数前实参值：",string)
    demo(string)
    print("调用函数后实参值：",string)
    print ("=======引用传递=======")
    list1 = ['1','2','3','4']
    print("调用函数前实参值:",list1)
    demo(list1)
    print("调用函数后实参值：",list1)